🤖 fix: cap expanded queued message height and make it scrollable (#3057)

## Summary

Cap the expanded queued message content at `40vh` and make it scroll on
overflow, so long queued messages no longer push the composer
off-screen.

## Background

When a queued message is expanded and its content exceeds viewport
height, the entire `ChatInputPane` grows unbounded—the Edit/Send now
buttons and the composer itself get displaced below the fold. This is
the same class of overflow that `AttachedReviewsPanel` already handles
with a viewport-relative height cap.

## Implementation

Wrapped `<UserMessageContent>` inside the expanded `QueuedMessageCard`
in an inner `<div className="max-h-[40vh] overflow-y-auto">` scroll
container. The action row (`Edit` / `Send now`) stays outside that
wrapper so controls remain always visible while the message body scrolls
independently.

---

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Author: ethanndickson

src/browser/features/Messages/QueuedMessage.tsx

@@ -82,12 +82,15 @@ export const QueuedMessage: React.FC<QueuedMessageProps> = ({
             className="border-border-medium bg-background-secondary/80 rounded-md border px-2.5 py-1.5"
             data-component="QueuedMessageCard"
           >
-            <UserMessageContent
-              content={preview.sanitizedText || preview.fallbackLabel}
-              reviews={message.reviews}
-              fileParts={message.fileParts}
-              variant="queued"
-            />
+            {/* Keep queued drafts bounded so long content never pushes the composer off-screen. */}
+            <div className="max-h-[40vh] overflow-y-auto">
+              <UserMessageContent
+                content={preview.sanitizedText || preview.fallbackLabel}
+                reviews={message.reviews}
+                fileParts={message.fileParts}
+                variant="queued"
+              />
+            </div>
 
             <div className="mt-1 flex flex-wrap items-center justify-end gap-x-2 gap-y-0.5">
               {onEdit && (